(1) Field of the Invention
The present invention relates to a device and method for controlling image display. The present invention especially relates to a display control technique for use by an image display apparatus that displays images by casting light from a light source onto a reflection-type display device, typified by an liquid crystal panel. According to the display control technique, the light source intensity is dynamically adjusted in relation to the correction of display image contents.
(2) Description of the Related Art
The following technique is disclosed regarding an image display apparatus that displays images on a liquid crystal panel. According to the disclosure, pixel data is attached with an error-detecting bit and an image display apparatus detects and corrects any errors in pixel data before display. Consequently, it is ensured that correct images are displayed (See Patent Document 1).
According to Patent Document 1, error correction is made on a pixel-by-pixel basis of display images generated. Thus, the error correction disclosed in Patent Document 1 is applicable to correct faults occurred in display images being transmitted on the path up to the image output unit. As a result of the correction, originally generated display images are recovered.
Another technique is disclosed regarding an image display apparatus that displays images on a liquid crystal panel. The technique aims to reduce the power consumption of a light source as well as to achieve the longevity of the display device. According to the disclosure, the adjustment values of the light source intensity are controlled in relation to the correction values of display images, with reference to various parameters including display images and readings of light and temperature sensors. As a result, power saving and extension of the device life is achieved (See Patent Document 2).
According to Patent Document 2, a correlation table is used to determine the adjustment values of the light source intensity and the correction values of display images, based on the features of the entire region of each display image, more specifically, the maximum, minimum and average values of luminance signals.
According to Patent Documents 1 and 2, it is ensured that if a fault occurs in a display image on an output path, a feature is extracted from the entire region of the display image having been corrected. Thus, the extracted features are more accurate than features extracted from display images without correction.
Usually, display images are compressed according to an image compression technique such as MPEG-2/4 or JPEG. An image display device receives compressed data from the outside and decodes the received compressed data to generate display images.
In the above process, the image display device according to Patent Document 1 conducts no processing for correcting decoding faults that may occur at the time of decoding compressed data or for correcting communication faults that may occur at the time of receiving the compressed data. That is to say, the generated display images may involve faults remain uncorrected.
For this reason, even in view of Patent Documents 1 and 2 in combination, there still is the following setback. If some kind of fault has occurred at the time of receiving or decoding compressed data, features are extracted from display images containing the faults. Thus, accurate features cannot be extracted. That is to say, the extracted features are incorrect. As a result, the processing for adjusting the light source intensity and the correction of display images are carried out based on the incorrect features. This may cause that the image quality is notably degraded or that the light source intensity is uselessly increased to cancel out the power savings. In addition, since the feature extraction is conducted on an entire region of each display image, the processing load is relatively heavy. In addition, if the display image involves a fault, the correction cannot be carried out appropriately.
In view of the above problem, the present invention aims to provide an image control device and an image display system that achieves energy savings without causing degradation of display images, even if image data contains a fault.
Patent Document 1: JP Patent Application Publication No. 2005-257854
Patent Document 2: JP Patent Application Publication No. 2002-202766